One of the most sought-after weapons for any operator tasked with entry is a short-barreled long gun. When working in close quarters and in close proximity to others, the short barrels are a huge asset. It is not that longer-barreled weapons don’t work—it’s just so much easier to move around debris, in and out of doors, and in close proximity to your partner with a short barrel.
Early on, this role was filled by the submachine gun in pistol chamberings, and it dominated this task. Anyone that has used a Heckler & Koch MP5 knows how fantastic that weapon was to use on operations. Its only real limitation was the caliber, and only then when engaging hard targets. Otherwise, it is still close to perfection when it comes to an entry platform. It has served professionals for decades due to its light weight, near perfect balance and 100-percent reliability with any ammunition.
Many of these weapons stayed in service for hundreds of thousands of rounds with nothing more than simple maintenance. They run in the heat, cold, dirt, dust—just about any environment. The roller-delayed blowback system deals with ammunition changes well and results in one of the softest-shooting weapons around. Muzzle rise and recoil are near non-existent, and holding on targets while moving is almost easy. The diopter sighting system has been so popular that it is copied today in many of the aftermarket sights designed for the AR platform. Other than the chambering, it was fantastic. What was really needed was the same weapon in 5.56x45mm.
The patriarch of the HK family of weapons is the G3. Based on the CETME Model B rifle, it was ultimately adopted as the Automatisches Gewehr G3 by the West German Army in the late 1950s. This was a 7.62x51mm select-fire weapon that operated from a closed bolt.